Heretofore, mesh bags have been used for various packaging applications including those in which breathability and visibility of the bags' contents are important features. Examples include produce bags for fruits, vegetables and other agricultural products and bags for sporting equipment, toys, blocks and various other small to medium size solid objects. Such bags have been made from solid plastic films, tubular packaging materials, such as VEXAR originated by E. I. du Pont de Nemours and Company, leno weave fabrics, knitted fabrics and flat woven fabrics, all of which are disadvantageous. For example, tubular materials require investment in specialty equipment to prepare bags from same (see, e.g., U.S. Pat. No. 4,091,595). Flat weave and knitted packaging materials, while avoiding complexities associated with tubular goods, are disadvantageous because they are typically sewn to form seams, thus adding to cost. Nonwoven fabrics seldom achieve a practical balance of strength and contents-visibility and they are often difficult to seam with appropriate strength. Plastic films lack breathability; attempts to overcome this limitation, such as by perforation, add cost, can impair strength and generally do not perform satisfactorily.
Beyond traditional attributes of produce bags, including strength, breathability and sufficient transparency or openness to allow viewing of their contents, high speed and automated bag-making and filling equipment have imposed additional requirements. To process well on high-speed bag-making equipment, bag substrates must track precisely through the equipment and remain in registration over the entire sequence of bag-making steps. The substrate must remain precisely in registration through repeated accelerations and decelerations so that each step of the bag-making operation, e.g., seaming, label application, die cutting, finished bag cut-off, is performed in precisely the right position on the bag. Dimensional stability of a bag substrate is important for such operations from the standpoint of maintaining registration and avoiding deformation as the material rapidly starts and stops during its progression through the bag-making equipment.
The substrate must also be a material that can be seamed with adequate strength to withstand filling operations, transportation and handling. Bags manufactured from mesh fabrics can be problematic in this respect, particularly those that comprise a delicate, net-like material and/or have only limited surface area available for seaming. Limited area for contact between opposite layers of the fabric tends to make heat sealed seams weak, if effective at all. Seaming with adhesives tends to be aesthetically unattractive. Sewn seams add cost and are often ineffective due to the small surface area of the open mesh fabric.
Attempts to produce an improved mesh bag have been further complicated by industry desire to incorporate printed or printable labels into the design of the bag, yet still preserve the efficiency of high-speed bag-making processes and maintain minimal cost and usage of label and mesh fabric materials. Examples of such attempts may be found in U.S. Pat. Nos. 6,190,044, 6,030,120 and 6,024,489 to Fox et al. The Fox et al. patents disclose a side-sealed bag, wherein one side of the finished bag is a mesh fabric and the other side of the bag is a film that serves as the label. Although the Fox et al. bags may be produced via high-speed bag-making machines, such bags are clearly disadvantageous, as half the bag is formed from costly film/label material, thus countering any savings that would ordinarily result from an efficient high-speed bag-making process.
Furthermore, the film material utilized to manufacture the Fox et al. mesh fabric/film bag is not as structurally durable as the fabric material (i.e., CLAF) utilized to manufacture the mesh fabric/film bag, as the film material is basically a low-density polyethylene/ethylene-vinyl acetate blend (LDPE/EVA), suited for use in continuous sealing equipment. The current Volm side sealed bag and Fox et al. tubed bags use oriented polyester or polypropylene films with linear LDPE (LLDPE) or similar material laminated thereto so as to allow heat-sealing of the films to the CLAF fabric. The need for the PET or OPP label materials arises from the need to apply the film/label in an intermittent mode, utilizing high temperatures (320 deg. F est.) and short dwell times.
Therefore, it is readily apparent that there is a need for a side-sealed mesh bag having a label section, wherein traditional attributes of conventional mesh bags, such as breathability and contents-visibility are provided, and high-speed bag-making machine criteria are met with minimal cost and usage of label and mesh fabric materials.